>book is up to date, it probably will discuss why the Cambrian explosion
>happened; if very up to date (highly unlikely that this has made it into
>textbooks), it will mention the increasing evidence that it extends well
>back into the Precambrian and was less explosive than has been thought.
Some perspective from an article in Time magazine (When life exploded,
article pointed out that all animal phyla except perhaps bryozoa are
present in early Cambrian, and that they all appear within a very small
slice of time ("no more than 10 million years")
Steven Gould "Fast is now a lot faster than we thought, and that's
Samuel a Bowring: "We now know how fast fast is, and what I like to ask my
biologist friends is, How fast can evolution get before they start feeling
Rudolph Raff: "There must be limits to change. After all we've had these
same old body plans for half a billion years."
G. M. Narbonne, Queens U. (paleontologist): "What Darwin deescribed in the
Origin of Species was the steady background kind of evolution. But there
also seems to be a non-Darwinian kind of evolution that functions over
extremely short time periods--and that's where all the action is."